The present invention relates to a method for the preparation of N-methyl-N-trimethylsilyl trifluoroacetamide or, more particularly, to an industrially advantageous method for the preparation of N-methyl-N-trimethylsilyl trifluoroacetamide without using corrosive reactants and with omission of the troublesome procedure of filtration to remove the precipitates of a by-product salt.
N-Methyl-N-trimethylsilyl trifluoroacetamide as the subject material of the inventive method is a useful compound as a neutral masking agent, i.e. a masking reactant for active hydrogen atoms utilizing the silyl group, in the semi-synthetic process of various antibiotics or derivatives thereof.
It is known and conventionally practiced in the synthetic preparation of N-methyl-N-trimethylsilyl trifluoroacetamide that N-methyl trifluoroacetamide is subjected to a dehydrochlorination reaction with trimethyl chlorosilane by adding the silane compound dropwise into a reaction mixture of N-methyl trifluoroacetamide and a tertiary amine compound, e.g. triethyl amine, as an acceptor of hydrogen chloride diluted with an organic solvent such as benzene, hexane and the like.
This method, however, is disadvantageous in several respects. For example, the reaction mixture after completion of the dehydrochlorination reaction must be filtered to remove the precipitates of the amine hydrochloride while the filtration cannot be performed without the problem of emission of a large volume of white fume by the reaction of the atmospheric moisture with the tertiary amine compound and trimethyl chlorosilane remaining in the reaction mixture to cause serious environmental pollution if not to mention the decrease in the yield of the product by the filtration and hydrolysis of the product compound during filtration. Moreover, the chlorosilane compound as one of the reactants is very corrosive against metals so that the production cost is necessarily high due to the expensiveness of the corrosion-resistant apparatus used in the preparation.